A Constant Shear Surface Direct Shear Apparatus

Abstract

The invention discloses a constant shearing surface direct shearing apparatus. The constant shearing surface direct shearing apparatus comprises a test bed, an upper shearing box, a lower shearing box, a vertical load loading mechanism and a horizontal load loading mechanism, wherein the lower shearing box is rotatably connected onto the test bed; the upper shearing box and the lower shearing box are internally provided with radial separation plates; the lower shearing box is driven by the horizontal load loading mechanism to rotate; a soil sample in the lower shearing box is pushed by the lower radial separation plate to have annular displacement; meanwhile, the upper shearing box is fixed and not moved and the upper radial separation plate is located at the lower half section and is used for stopping the soil sample in the upper shearing box from the annular displacement in a shearing process; the lower shearing box is rotated so that the soil samples in the upper shearing box and the lower shearing box mutually have the shearing displacement, and furthermore, the aim of annular direct shearing is realized; in a whole shearing process, the shearing area of the soil samples keeps constant all the time and negative stress is not changed so that tested data is accurate and calculated soil engineering data is very reliable.

Description

technical field [0001] The invention relates to a device for measuring the strength characteristics of soil materials, in particular to a direct shear instrument. Background technique [0002] The direct shear test has the advantages of convenience and economy, and is widely used in civil engineering. The principle is to put the cut soil sample into the upper and lower parts of the shear box, and apply a certain vertical load to the soil sample through the top pressure plate, so that the upper and lower parts of the shear box press A certain speed is relatively horizontally staggered, and the soil sample is sheared accordingly, so as to obtain the shear strength of the soil sample. [0003] At present, due to design defects, existing direct shear instruments generally have deficiencies. During the direct shear test, as the shear displacement increases, the effective shear area gradually decreases, and the normal stress on the shear surface also changes accordingly, result...

AI Technical Summary

Problems solved by technology

[0003] At present, due to design defects, existing direct shear instruments generally have deficiencies. During the direct shear test, as the shear displacement increases, the effective shear area gradually decreases, and the normal stress on the shear surface also changes accordingly, resulting in the shear strength measured by the test inaccurate, by and Cohesion c and internal friction angle Correspondingly unreliable

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